1. Field of the Invention
This invention relates to apparatus for a slipless conveyance of two plates, particularly of glass plates, which are coextensive and in register and parallel to each other and transversely spaced apart and are supported at those broadsides which are remote from each other and define respective planes of travel, which may be inclined, vertical or approximately vertical, or horizontal.
2. Description of the Prior Art
Such an apparatus has been described in DE 30 38 425 C2. By that known apparatus, glass panes which are provided with adhesive joints at their edges are conveyed in an approximately vertical orientation. The insulating glass pane provided with adhesive edge joints consists of two glass plates, which are interconnected by a spacer frame, which is coated with adhesive on both sides. The bars of the spacer frames are slightly shorter than the associated edges of the glass plates so that the two glass plates define between them on the outside of the spacer frame an edge groove, which is filled with a sealing compound to prevent an ingress of moisture into the interior of the insulating glass pane.
The apparatus known from DE 30 38 425 C2 comprises a bottom edge-supporting conveyor having supports which contact the bottom edge of the glass plates while leaving the bottom edge groove free and which are synchronously moved in the direction of travel of the apparatus so that said supports convey the insulating glass pane. The insulating glass pane is laterally supported by backing rollers, which are arranged in a row and contact the rear glass plate of the insulating glass pane. The forward glass plate of each pane is supported by means of the spacer frame on the rear glass plate. To prevent a slip of the insulating glass panes being conveyed and to prevent also a slipping of the insulating glass pane from the supports, which laterally project only slightly under the pane, the supports are L-shaped and their horizontal arms contact the bottom edges of the glass plates whereas the rising arms constitute jaws which apply pressure to the outside surfaces of the two glass plates.
The apparatus which is known from DE 30 38 425 C2 has the disadvantage that the impact of the bottom edge-supporting conveyor on the bottom edge of the glass plates sometimes results in a splintering or fracture of glass. Another disadvantage of the known apparatus resides in that it cannot be used to convey pairs of transversely spaced apart, parallel glass plates which are in register but have not yet been joined to each other. An apparatus which can be used for that purpose has been described in DE 28 20 630 A1. The apparatus known from that printed publication comprises a horizontally conveying bottom edge-supporting conveyor, which consists of synchronously driven rollers, which are arranged in pairs mounted on respective axles and coupled by a friction coupling. The apparatus also comprises an array of backing rollers for supporting one glass plate on one broadside. The backing rollers of said array are tangent to a common plane. Above the bottom edge-supporting conveyor the apparatus comprises a beam, which is parallel to said conveyor and is adjustable in height and carries additional backing rollers, which are arranged in a row in front of the tangenital plane of the backing roller array and are also tangent to a common plane, which is spaced a corresponding distance from the tangential plane of the backing roller array. Besides, the known apparatus is mounted to be reciprocable parallel to itself so that the apparatus can be reciprocated between positions in which the parallel tangential planes of the backing roller array and of the row of backing rollers coincide with the plane of travel of single consecutive glass plates conveyed by a preceding horizontal conveyor. The leading glass plate of a pair is caused to enter the apparatus when the tangential plane of the row of backing rollers coincides with the plane of travel of the glass plates on the preceding horizontal conveyor. The second glass plate of a pair is caused to enter the apparatus when the tangential plane of the backing roller array coincides with the plane of travel of the plates on the preceding horizontal conveyor. As a result, the glass plates can be arranged in the apparatus to form pairs of transversely spaced apart glass plates which are coextensive and in register and can be synchronously conveyed further without being joined. But the known apparatus has the disadvantage that the initially leading glass plate of each pair may laterally slip at its bottom edge, that a slipless conveyance is not ensured because the coupling between the glass plates and the rollers of the bottom edge-supporting conveyor will depend on the weight of the glass plates, and that the backing rollers of one row which are used to support the initially leading glass plate of each pair extend into the space between the glass plates to that the gap at the top edges of the two glass plates is not entirely exposed. Another disadvantage of the known apparatus resides in that it can be used to convey glass plates only when they have an almost vertical orientation rather than a strongly inclined or even horizontal orientation.